n^ 



NA TURE 



[November 24. 1923 



The Water Supply or Nyasaland. — There exist 

 in Nyasaland large tracts of fertile land which are 

 deficient in water supply. If this defect could be 

 remedied these areas would be available for settle- 

 ment by natives or Europeans. In Water Supply 

 Paper No. i, issued as a supplement to the Nyasaland 

 Government Gazette of June 30, Dr. F. Dixey considers 

 the possibilities offered by underground water. The 

 rainiall of Nyasaland varies from 30 to 80 inches a 

 year, but the long dry season which follows the rainy 

 season leads to ^eat evaporation of surface water. 

 In consequence, m any improvement of the supply, 

 resource must be had chiefly to underground supplies. 

 The granites, gneisses, and schists of the country 

 are not too favourable in this respect, but in the 

 Shire valley there are extensive alluvial deposits and, 

 west of the Shire river, sandstone and shales overlie 

 the crvstalline rocks. It is in the last-named rocks 

 that the problem is most difficult of solution. Dr. 

 Dixey compares the conditions with those obtaining 

 in Southern Rhodesia, where at shallow depths an 

 appreciable supply of water is obtained from percola- 

 tion in joints and fissures. He believes also that a 

 certain supply may be obtained from shallow depres- 

 sions, known as " pans " or " vleys," which indicate 

 a considerable depth of weathered rock. In areas 

 unfavourable for wells, the construction of im- 

 permeable collecting slopes and storage tanks is 

 recommended. On such a slope a rainfall of 20 inches 

 should yield 450,000 gallons per acre. 



Variability of Tropical Climates. — A series of 

 articles have appeared in the issues of the Meteoro- 

 logical Magazine for July, August, and September by 

 Dr. Stephen S. Visher (Chicago) on the above subject. 

 The opinion is held that the general emphasis upon 

 uniformity in the tropics is misleading, and attention 

 is directed to the variations of temperature and wind, 

 while rainfall in lower latitudes is shown to be more 

 variable on the average than the rainfall of higher 

 latitudes. For seasonal range of temperature, amongst 

 many other places. Hong Kong in latitude 22° N. with 

 a range of 20° F, is compared with Glasgow in latitude 

 56° N. with a range of 12° F. It is pointed out that 

 the latitude of Switzerland receives much more heat 

 from the sun on June 21 than the equator, for the 

 sun at that time is about equally vertical in the two 

 places, while in Switzerland the days are about 

 4 hours longer. Cold snaps are shown to occur 

 commonly in the tropics from various causes. With 

 respect to variability of rainfall, comparison is made 

 between the wettest and driest years in tropical 

 regions and those in higher latitudes. The wettest 

 years out of the tropics seldom exceed more than 

 double the rain of the driest years, while in the tropics 

 the variation of range is much greater. An important 

 factor in these comparisons is the length of the period 

 dealt with ; this is recognised by the author. The 

 total rainfall in wettest years is very much larger in 

 tropical regions than in higher latitudes. The 

 erratic nature of cyclonic storms in different parts of 

 the world is referred to, and for frequency and 

 violence the extremes are said to be greatest in low 

 latitudes. 



Atomic Weight of Boron. — We have received a 

 copy of vol. 59, No. 2 of the Proceedings of the 

 American Academy of Arts and Sciences, which 

 contains a paper by Baxter and Scott on a revision 

 of the atomic weight of boron. Taking silver as 

 107-88, these workers find that boron is 10-82 from 

 analyses of the trichloride and tribromide of boron. 

 Improved methods for the fractional distillation in 

 vacuum of boron haUdes are also described. 



Synthesis of Lecithin. — Dr. A. Grfin .nii 

 R. Limp&cher reported to the conf^ress of Ger 

 chemists, recently held at Jena, that older dp ; 

 tions, which had been taken for artificial le* : 

 were nothing but choline salts of glycero-phoep 

 acid. True lecithin is obtained oy the acti< 

 diglycerides upon phosphoric anhydride, and 

 sequent action of choline bicarbonate. The pur 

 product has all the physical and chemical properties 

 of the lecithin prepared from seeds, egg-yolk, and 

 the substance of nerves and brain. Optically active 

 lecithins are also obtainable in this way ; the 

 kephalines can be prepared from diglyceride, phos- 

 phoric anhydride, and colamine. 



Nitrogen Content of Wheat Grain. — The 

 importance of a high nitrogen content of the whr-nt 

 grain has led Olson (Journ. Agric. Res. xxiv., 

 to attempt to ascertain whether this can be van- 

 alteration in the controllable conditions in the en-. 

 ment of the wheat plant. The nitrogen c<< 

 seemed to be increased by widening the di-' 

 between the drills when no irrigation was ap, 

 but under irrigation in another district this effect w.i- 

 not obtained. On the other hand, irrigation per se 

 exerted no influence in either direction. As mat ■ 

 approached, the nitrogen in the plant moved to 

 the grain, though the actual percentage in the 1 tin 1 

 decreased, apparently owing to the more rapid in- 

 filling of carbohydrates. It would appear that ! "•■•'- 

 quantities of water are required to move the : 

 genous matter than the non-nitrogenous into ;.. 

 grains, and accordingly an ample supply of water 

 should prove beneficial to high rather than to low 

 nitrogen content, which rather contradicts the findings 

 with regard to irrigation. Phosphorus and nitrogen 

 were found to enter the grain simultaneously, thus 

 corroborating the results of other investigators. 



Lead and Plants. — The application of radio- 

 active isotopes as indicators, mainly by Hevesy and 

 Paneth, has proved to be a powerful method of 

 attacking many physico-chemical problems that do 

 not readily lend themselves to direct methods. A 

 further interesting application of this method i- 

 given in the current issue of the Biochemical J 

 (vol. xvii. pp. 439-445, 1923) by Prof. W 

 (Copenhagen), who has investigated the " Absorption 

 and Translocation of Lead by Plants." Specimens 

 of Vicia Faba (horse-bean) were immersed in lead 

 nitrate solutions of different concentrations contain- 

 ing thorium B (isotope of lead) as an indicator, and 

 after ignition of the various parts of the plant their 

 lead content could be found by radioactive measure- 

 ment of the ash. Quantitative results have been 

 obtained using solutions varying in concentration 

 as much as from lo"* N. to 10-' N. In 24 hours the 

 root of the plant absorbed in the former case 60 p>er 

 cent, of the lead contained in 200 c.c. of the solution, 

 whereas in the latter case only 0-3 per cent, was 

 absorbed. The amount of lead passing into the stem 

 and leaves is less than i/io per cent., and does not 

 vary greatly with the solution concentration, indicat- 

 ing that most of the assimilated lead is bound to the 

 root, and experiments on displacement show that it 

 is associated in the form of a dissociable but not 

 readily soluble salt, and not in combination with 

 carbon. Whereas a lO"^ N. solution of a lead salt 

 produces toxic effects on the plant even after 24 hours, 

 more dilute solutions do not. Experiments on the 

 kinetic displacement of assimilated ions by other ions 

 are described in conne.xion with the phenomenon of 

 " antagonism," according to which certain ions have 

 the capacity of inhibiting the toxicity produced by 

 others. 



NO. 



2821, VOL. 112] 



